Damo, if you are looking at a kit, you might want to check out this link
http://www.justjap.com/forumcoolerkitspecial.htm
To fit the kit you will need a 3 inch hole saw to create the hole in the inner guard.
Wether the fan blades need to be clipped or not depends on the kit you use and how its fitted. At worst a small trim on the edge of the each blade should be all thats required, and this wont cause any problems with the "balance" of the fan blades.
Cheers,
Nick